FI87865C - FOERFARANDE FOER AVSTAEMNING AV EN FILTER SAMT EN FOER TILLAEMPNING AV FOERFARANDET AVSEDD FILTER - Google Patents

Description

87865

METHOD OF TUNING THE FILTER AND THE FILTER FOR APPLYING THE METHOD - FOR SUSPENSION OF THE FILTER SAMT OF THE SAMPLING OF THE METHOD

The present invention relates to a method for tuning a filter according to the preamble of claim 1 and to a filter for applying the method.

Especially at higher frequencies, e.g. from a few hundred to 10 MHz upwards, it is difficult to determine the "ideal" capacitance or inductance of the LC component. Changes in the physical structure and dimensions of the components, as well as changes in the operating environment, affect e.g. significantly to the total capacitance and inductance. In the frequency range 100 ... 10000 Mhz 15, for example, the capacitor's own, even straight-through connection conductors and its own capacitance can be used to form serial and parallel resonant circuits or even combinations thereof, e.g.

20 In accordance with the invention, the so-called the diffuser ductances and capacitances can be tuned to the LC circuit. The basic tuning is performed by selecting a suitable capacitance value close to the correct capacitance and an inductance value suitable for the frequency based on the length of the capacitor connection wires. '25 In this case, the suitability of the LC ratio for the intended use must also be taken into account. Finally, the filter is tuned according to the characterizing part of claim 1 by changing the position of the filter components and the connecting conductors with respect to the inner surface of the housing.

According to the invention, with a small number of components, high quality RF filters can be implemented in the VHF frequency range and upwards.

2,87865

The invention achieves the following advantages over the prior art: There are few loss-causing components.

5 Lossless connection plate trays are not required.

There is no possibility of failure caused by shaft-adjustable components, eg trimmers.

10

The minimum number of components optimizes reliability and economy.

The filters according to the invention are easy to manufacture and adjust.

15

In the following, the invention will be described in more detail by means of examples with reference to the accompanying drawings, in which

Figure 1 shows a top view of a 1 GHz / radio filter 20 according to the invention.

Figure 2 shows a side view of a filter according to the invention.

Figures 3-5 show typical filter emission and blocking attenuation values.

Figure 6 shows a 900 MHz / 450 MHz filter according to the invention.

Figure 7 shows a 900 MHz / 450 MHz / radio filter according to the invention.

The filter shown in Figures 1 and 2 has a plate-like, metallic housing structure 1 folded on each side.

35 The housing structure can be either the filter housing or the entire radio or telephone housing. The filter has an antenna connector 2 3 87865 for the antenna connection in the middle and a 3 900 MHz connector for the telephone connection on one side (above in the figures) and a connector 4 for the radio connection (<500 MHz) on the other side (below the figures).

5

The antenna connector 2 and the telephone connector 3 of the 900 MHz band are connected to each other by a capacitor C.j soldered to their base at a suitable distance from the inner surface of the housing 1, having connecting wires and s12. The antenna connector 2 and the radio connector 4 are connected to each other by a connecting wire s2 soldered to their base and bent at a distance suitable for the inner surface of the housing 1. In addition, the base of the radio connector 4 is

As described above, according to the invention, the filter is tuned using the stray inductances and capacitances of the capacitor and the connecting wire S2 in a controlled manner. The basic tuning is performed by selecting a suitable capacitance value close to the correct capacitance as the capacitor C120 and an inductance value suitable for the frequency based on the length of its connecting wires s ^ and s ^ 2. The final tuning is performed by changing the position of the capacitance part and its connection conductors with respect to the inner surface of the device housing 1 in the lateral and vertical directions according to the arrows. Correspondingly, a suitable length of the connecting conductor s2 and a distance from the inner surface of the housing 1 are initially selected. The final tuning is done as in the case of capacitor C.j by moving it according to the arrows.

: The capacitor with its connecting wires forms a series resonant circuit which passes the 900 MHz signal, and the capacitor C2 prevents the 900 MHz signal from entering the terminal 4. Correspondingly, the radio signal is passed to the terminal 4 and its access to the terminal 3 is prevented.

Figures 3 and 4 show typical values of pass and suppression attenuation for the filter of Figures 1 and 2 at ports 3 to 4 87865 2-3 and 4-2-4 900 MHz. It can be seen from Figure 3 that the emission attenuation is typically less than 0.1 dB, and from Figure 4 that the blocking attenuation is at most about 52 dB and at its lowest about 35 dB. Figure 5 also shows emission-5 attenuation for frequencies below 500 MHz at gate 4-2-4, which shows that the emission attenuation is typically less than 0.25 dB.

Figure 6 shows a 900 MHz / 450 MHz filter with pe-10 terminals terminals 2, 3 and 5 and a capacitor in terminal 3 for blocking a 450 MHz signal, a capacitor passing a 900 MHz signal between terminals 2 and 5 C4, which emits a 450 MHz signal, and in terminal 5, a capacitor C,., Which blocks a 900 MHz signal. 15 In capacitors and there are Connection wires s1 ^, ss4 <j and s421 There is also a 900 MHz / 450 MHz / radio filter shown in Fig. 7, in which terminals 2 to 5 are placed at the corners of a square, and in which, in addition to the components described above, capacitor Cg 450 For filtering the MHZ sig-20 signal at terminal 4. The filters of Figures 6 and 7 are tuned as described above in connection with Figures 1 and 2.

It will be apparent to those skilled in the art that the various embodiments of the invention are not limited to the examples set forth above, but may vary within the scope of the claims set forth below.

Claims (4)

A method for tuning a filter consisting of either a separate metal pitch (1) or with the other apparatus 5, common metal pitch (1) and connectors (2 ... 5), of which at least one (2) can be connected to a receiving / transmitting antenna of a signal and at least one (3 ... 5) can be connected to a radio / telephone operating within a certain frequency range for receiving / transmitting a signal, and between which connectors a connection conductor (s2) or by means of connection conductor ( one or more filtering components (C ^, C4) which allow the frequencies for the radio / telephone to pass and block the frequencies not intended for the radio / telephone, the component values and the connection values of the filtering components. the lengths of the conductors are selected to be suitable for the intended filtering, characterized in that the filter is tuned by changing the positions of the filtering components and the connecting conductors. howling to the inner surface of the housing (1). 2. Filters for applying the method according to the claim, ·. : 1, which filter consists of either a separate or with the 7. · other equipment common metal height (1) and connection. . Means (2 ... 5), of which at least one (2) can be connected to an antenna for receiving / transmitting a signal and at least one (3 ... 5) can be connected to one within a certain frequency range operating radio / telephone for receiving / transmitting a signal, and between which connectors are connected a connecting conductor (s2) or by means of connecting conductors ^ sll's12, s41, s42 ^ one or more filtering components (ClfC4) which allows the frequencies for the radio / telephone to pass and block those frequencies not intended for the radio / telephone, which component of the filtering components and the values and lengths of the connecting conductors are chosen so that the β ίί 7 S 6 5 suitable for the intended filtration, characterized in that the filtering components and connecting conductors are so connected to the connectors that their positions can be changed relative to the inner surface of the housing (1) in such a way that the filter can be adjusted the positions of the filtering components and the connecting conductors are changed relative to the inner surface of the housing (1). Filter according to claim 2, comprising at least one terminal (3.5) for the frequency range above 400 MHz, characterized in that the terminal (3,5) is connected to the antenna terminal via a filtering capacitor (C C, C ^). . Filter according to Claim 2 or 3, comprising at least one connector (4) for the frequency range below 400 MHz, characterized in that the connector is connected to the antenna connector via a connector (S2) and between the base of the connector (4) and a location 20 at the housing is a filtering component (c2'c6 ^ for filtering the frequency range above 400 MHz.